Smooth, stable and high quality game image is provided by accurately pre-reading background data required for image processing each time. The game device therefore reads background data required for a game that displays a condition of a moving vehicle within a virtual three-dimensional space together with a background in the main memory from a CD-ROM (recording medium) prior to image processing. This device comprises a pre-reading unit for pre-reading background data from a recording medium when reading a start line (reference line) set at a distant position in a specified distance away from the limit line of the visual field direction of display is crossing a new area. A recording medium is a medium that records background data by dividing it into a plurality of areas in advance, and the pre-reading unit comprises a unit for judging on which of the areas the reference line is crossing, and a reading unit for reading in memory the background data of the area judged as being crossed with the reference line.